Getting Started

Education: Genotyping MiniCourse

This MiniCourse is an introduction to all things genotyping.

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Blog: Designating Genotypes

Introduction to basic terminology that is used in genotyping protocols

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The Why’s and When’s of Genotyping Your JAX Mice

Have you ever started an experiment with a newly arrived mouse strain, but then had unexpected results? You may have then genotyped the mice and discovered that they were not the genotype that you expected. This can be a frustrating experience that wastes time and causes unnecessary extra work. This is just one example of a scenario where genotyping your mice is important.

An essential step in mouse breeding is genotyping your mice to ensure that they have the expected genotype. The genotype for a specified gene in a mouse can be homozygous, heterozygous, wild type, and sometimes hemizygous (such as X-linked genes or transgenes). You may even have multiple genes with multiple genotypes in one mouse. The genotype of your mouse determines the phenotype. Therefore, a homozygous mouse will have different characteristics than a heterozygous mouse. For this reason, it is important to routinely genotype your mice to maintain consistency with your mouse colonies.

There are three scenarios when you should genotype your mice.

1. When you receive new mice.

You should genotype mice when you receive them, regardless of the source -you should genotype your mice whether you got them from a reliable vendor such as The Jackson Laboratory, from a collaborator, or any external source. In this scenario, genotyping the mice makes sure that they are the expected genotype, and have not gotten mixed up with other mice during shipping. We recommend that you genotype before you breed the mice so that you don’t waste valuable research time breeding mice with an unwanted genotype.

2. When setting up new breeder pairs.

If you are already maintaining a colony in your facility, you should continue to genotype your mice every time you set up new breeder pairs, even if you are maintaining a homozygous colony. You should genotype both the female and the male to ensure that they both have the expected genotype. This will help prevent breeding errors, keeping you from losing valuable research time. The sooner you catch a mistake, the faster that you can move forward.

3. When multiple genotypes are produced with your breeding scheme.

Depending on the genotypes of the breeders, you may need to genotype all of the pups. A homozygous x homozygous breeding pair will produce only homozygous mice, so the pups do not need to be genotyped. However, a heterozygous x heterozygous breeding pair will produce homozygous, heterozygous, and wild type mice. You will therefore need to genotype the breeders before setting them up to breed and then genotype each pup.

Ready to genotype? You can start by finding the genotyping protocol for your JAX strain.


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